1. Field of the Invention
The invention is directed generally to wind turbine blade design.
2. Description of the Related Art
Wind turbine blades are comprised of shells and other structural components which may be thickest near the base, or root, of the blade. The weight of these components in regions near the midpoint of the blade and beyond becomes a key factor in reducing blade deadweight moment, while the weight of such components near the blade root is comparatively less important. The use of premium materials, which have a high stiffness or strength to weight ratio, may enable the weight of these components to be reduced, and may significantly improve blade properties. However, these premium materials may be more expensive than other materials. Optimization of the use of such premium materials may provide significant cost savings, as well as better mechanical performance.
Use of premium material only in the outer blade is possible by means of a material transition zone joining plies of premium fiber to other material. Such a material transition zone is difficult to build into the limited internal volume of the outboard blade sections, due to extra thickness needed in the material overlap region to transition working strains and overcome stress raisers from starting and ending material layers.